This invention refers to equipment for the recycling of polyolefinic plastic sheeting material, in which the equipment is of the type that comprises the following: [i] at least one breaker mechanism for the plastic material being recycled; [ii] at least one initial separating device to separate materials of higher density than that of this plastic material by means of flotation; [iii] at least one crushing mill to reduce this plastic material to small particles; [iv] at least one water-based separating tank that, on the one hand, is equipped with several blades for surface displacement of these small particles and, on the other, is equipped with a bottom with an outlet; each separating tank being equipped with a suitable feeder to receive the plastic material that has been crushed and, at least partially, separated from materials of higher density, delivering such material to the area near this bottom, there being an initial variable speed motor suitable to controlling this delivery; [v] means to separate this plastic material from this water; and [vi] means to bind the plastic material.
In particular, the aforesaid equipment refers to polyolefinic filler-free plastic sheeting material originating from sorted and separated rubbish, in other words, after being used (post-consumer) in polyethylenes (PE), polypropylenes (PP), ethylene vinyl acetate (EVA) and polybutylenes (PB); from now on, this description and these claims refer solely to these plastic materials, which have density (when not filled) under 1 g/cm3.
As is known, the consumption of plastic sheeting materials is increasingly more frequent, being used preferably for wrappings and also to make container bags. This plastic sheeting material is normally thrown away after use, a fact that poses significant ecological problems, particularly when considering that the majority of these plastic materials are not biodegradable. As a result, current regulations and world-wide trends are encouraging recycling by creating infrastructures for the collection, sorting and recycling of plastics, such as containers and packing materials.
By recycling this plastic sheeting, the regulations are enforced, pollution decreases and an economic benefit is obtained through reduced imports of petroleum, from which these plastics are derived.
Nevertheless, typically existing facilities have disadvantages, among them we should mention those covered by the following remarks.
One of the important elements for a facility to recycle polyolefinic plastic sheeting material is that it consist of one or more water separating tanks; these have an inverted trunco-conical bottom and when there are more than one, these tanks are connected one above the other, thereby creating levels between the tanks; in addition they have identical descending vertical feeders, that are immersed in the aforesaid tanks and, by means of screw conveyors, carry the chopped plastic material to the area near the bottom of the separating tank.
Once there, the plastic material having a density lower than water, tends to rise toward the surface of the water in the tank. In contrast, materials with a higher density, plastics, etc. (and that cannot be used) tend to remain at the bottom of the tank and an adjustable outlet is provided for drainage for each vertical tank.
In each vertical tank, the water and general liquids contained in the tank should be very clean; this need involves the renovation of this water and, therefore, a water discharge offset by a clean water entry.
Moreover this water discharge evidently involves draining the sludge, impurities and plastic particles of higher density than water that, therefore, are found near the bottom of the tanks, frequently associated to other particles of lower density.
Consequently, the function of the aforesaid adjustable outlet is to control the amount of water (together with disposable sludge, impurities, plastic particles and others) that must exit the vertical tank to be conveyed toward the strainer.
In existing facilities, the structure of each adjustable outlet is as follows: an elbow pipe fitting connects the lower vertex of the liquid tank to the top of a strainer located below the maximum water level of the tank; the bottom of this strainer (which is where the drainage mouth thereof is located) is at a level below the liquid inlet and between both areas there is a wire gauze, a perforated plate, a grill or similar object, placed at a tilted position and used to separate the water from the aforesaid disposable sludge, impurities, plastic particles, etc.
The amount of water that exits the tank is proportional to the smaller inner cross-section of the elbow pipe fitting and to the height difference between the water level in the tank and the height of the aforesaid inlet to the strainer.
Therefore, one of the factors indicated in the above paragraph must be varied in order to regulate the aforementioned amount of water; since it is not easy to change the aforesaid height difference (which would involve vertical displacement of heavy bodies), the regulation must be obtained by varying the aforesaid cross-section and this variation is not possible by means, for example, of a butterfly valve or other kind of existing valve, since they could easily result in a jam due to the unavoidable retention of the sludge, impurities and plastic particles present in the water.
Consequently, this necessary regulation is handled in typically existing facilities by using a variety of gauges and making appropriate substitutions on a case-by-case basis.
Evidently this regulation has disadvantages of some importance, since it is necessary to have an initial valve upstream from the place where these gauges are located and a second valve downstream from the place where these gauges are located; to close the valves with the resulting halt of the process; to replace the gauge and to reopen the aforesaid valves in order to continue the process.
The invention is intended to overcome these drawbacks; this purpose is achieved with equipment of the type indicated above, in which the equipment is characterised in that it has a pump equipped with the following: an inlet connected to this outlet, an outlet, several moveable devices suitable for promoting suction flow of this water and these materials through this inlet and a propulsion flow of this water and these materials through this outlet, and a second motor suitable for driving these moveable devices, with this second motor being of suitable speed to allow variation such that this speed variation of this second motor causes a variation in the flow rate of these flows.